High-field phase diagram and unusual memory effect of Ni₃V₂O₈.

(Phys. Rev. B 97, 174429, 2018)

Background

Since 2003, multiferroics have become the research focus in condensed matter physics due to rich physical properties and potential application in storage device. Among multiferroics, the materials in which magnetic fields induce ferroelectricity are called type-II multiferroics and have strong magnetoelectric coupling and magnetoelectric memory effect.

What we discover?

Here we report an experimental observation of unusual magnetoelectric memory and polarization reversal in the kagome staircase compound Ni₃V₂O₈. The explored ferroeletric phase in 19-24 T is electrically controlled, whereas the ferroelectric phase in 2-11 T exhibits unusual memory effects. We determine a characteristic critical magnetic field H₃=11 T, below which strong memory exists and the polarization is frozen even in opposite bias fields. But when magnetic fields exceed H₃, the frozen polarization is released and polarization reversal appears by tuning bias electric fields.

Why is this important?

It has been reported that some multiferroic materials possess magnetoelectric memory effect. However, mechanism of this memory effect has been still on debate. Unusual magnetoelectric memory and polarization reversal was firstly reported in our pulsed-field polarization measurements on Ni₃V₂O₈. The pinning-depinning mechanism was therefore proposed and can well explains these experimental phenomena.

Why did they need WHMFC?

The magnetic and ferroelectric phases that explored in this study are driven by sufficient high magnetic fields. Wuhan National High Magnetic Field Center provides great technical support during high-field magnetization and high-field polarization measurements.

Who did the research?

Y. J. Liu,¹ J. F. Wang,^1,* Z. Z. He,² C. L. Lu,¹ Z. C. Xia,¹ Z. W. Ouyang,¹ C. B. Liu,¹ R. Chen,¹ A. Matsuo,³ Y. Kohama,³ K. Kindo,³ and M. Tokunaga ^3,*

¹ Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China

² State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, China

³ The Institute for Solid State Physics (ISSP), University of Tokyo, Chiba 277-8581, Japan